提交 1ce53adf 编写于 作者: D Denys Vlasenko 提交者: Michal Marek

modpost: support objects with more than 64k sections

This patch makes modpost able to process object files with more than
64k sections. Needed for huge kernel builds (allyesconfig, for example)
with -ffunction-sections. 64k sections handling is covered, for example,
by this document:

"IA-64 gABI Proposal 74: Section Indexes"
http://www.codesourcery.com/public/cxx-abi/abi/prop-74-sindex.htmlSigned-off-by: NDenys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: NAnders Kaseorg <andersk@mit.edu>
Acked-by: NSam Ravnborg <sam@ravnborg.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>
上级 4696e295
......@@ -839,16 +839,16 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
char *zeros = NULL;
/* We're looking for a section relative symbol */
if (!sym->st_shndx || sym->st_shndx >= info->hdr->e_shnum)
if (!sym->st_shndx || get_secindex(info, sym) >= info->num_sections)
return;
/* Handle all-NULL symbols allocated into .bss */
if (info->sechdrs[sym->st_shndx].sh_type & SHT_NOBITS) {
if (info->sechdrs[get_secindex(info, sym)].sh_type & SHT_NOBITS) {
zeros = calloc(1, sym->st_size);
symval = zeros;
} else {
symval = (void *)info->hdr
+ info->sechdrs[sym->st_shndx].sh_offset
+ info->sechdrs[get_secindex(info, sym)].sh_offset
+ sym->st_value;
}
......
......@@ -253,7 +253,7 @@ static enum export export_no(const char *s)
return export_unknown;
}
static enum export export_from_sec(struct elf_info *elf, Elf_Section sec)
static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
{
if (sec == elf->export_sec)
return export_plain;
......@@ -373,6 +373,8 @@ static int parse_elf(struct elf_info *info, const char *filename)
Elf_Ehdr *hdr;
Elf_Shdr *sechdrs;
Elf_Sym *sym;
const char *secstrings;
unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U;
hdr = grab_file(filename, &info->size);
if (!hdr) {
......@@ -417,8 +419,27 @@ static int parse_elf(struct elf_info *info, const char *filename)
return 0;
}
if (hdr->e_shnum == 0) {
/*
* There are more than 64k sections,
* read count from .sh_size.
* note: it doesn't need shndx2secindex()
*/
info->num_sections = TO_NATIVE(sechdrs[0].sh_size);
}
else {
info->num_sections = hdr->e_shnum;
}
if (hdr->e_shstrndx == SHN_XINDEX) {
info->secindex_strings =
shndx2secindex(TO_NATIVE(sechdrs[0].sh_link));
}
else {
info->secindex_strings = hdr->e_shstrndx;
}
/* Fix endianness in section headers */
for (i = 0; i < hdr->e_shnum; i++) {
for (i = 0; i < info->num_sections; i++) {
sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name);
sechdrs[i].sh_type = TO_NATIVE(sechdrs[i].sh_type);
sechdrs[i].sh_flags = TO_NATIVE(sechdrs[i].sh_flags);
......@@ -431,9 +452,8 @@ static int parse_elf(struct elf_info *info, const char *filename)
sechdrs[i].sh_entsize = TO_NATIVE(sechdrs[i].sh_entsize);
}
/* Find symbol table. */
for (i = 1; i < hdr->e_shnum; i++) {
const char *secstrings
= (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset;
for (i = 1; i < info->num_sections; i++) {
const char *secname;
int nobits = sechdrs[i].sh_type == SHT_NOBITS;
......@@ -461,14 +481,26 @@ static int parse_elf(struct elf_info *info, const char *filename)
else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
info->export_gpl_future_sec = i;
if (sechdrs[i].sh_type != SHT_SYMTAB)
continue;
if (sechdrs[i].sh_type == SHT_SYMTAB) {
unsigned int sh_link_idx;
symtab_idx = i;
info->symtab_start = (void *)hdr +
sechdrs[i].sh_offset;
info->symtab_stop = (void *)hdr +
sechdrs[i].sh_offset + sechdrs[i].sh_size;
sh_link_idx = shndx2secindex(sechdrs[i].sh_link);
info->strtab = (void *)hdr +
sechdrs[sh_link_idx].sh_offset;
}
info->symtab_start = (void *)hdr + sechdrs[i].sh_offset;
info->symtab_stop = (void *)hdr + sechdrs[i].sh_offset
+ sechdrs[i].sh_size;
info->strtab = (void *)hdr +
sechdrs[sechdrs[i].sh_link].sh_offset;
/* 32bit section no. table? ("more than 64k sections") */
if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) {
symtab_shndx_idx = i;
info->symtab_shndx_start = (void *)hdr +
sechdrs[i].sh_offset;
info->symtab_shndx_stop = (void *)hdr +
sechdrs[i].sh_offset + sechdrs[i].sh_size;
}
}
if (!info->symtab_start)
fatal("%s has no symtab?\n", filename);
......@@ -480,6 +512,21 @@ static int parse_elf(struct elf_info *info, const char *filename)
sym->st_value = TO_NATIVE(sym->st_value);
sym->st_size = TO_NATIVE(sym->st_size);
}
if (symtab_shndx_idx != ~0U) {
Elf32_Word *p;
if (symtab_idx !=
shndx2secindex(sechdrs[symtab_shndx_idx].sh_link))
fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n",
filename,
shndx2secindex(sechdrs[symtab_shndx_idx].sh_link),
symtab_idx);
/* Fix endianness */
for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop;
p++)
*p = TO_NATIVE(*p);
}
return 1;
}
......@@ -514,7 +561,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
Elf_Sym *sym, const char *symname)
{
unsigned int crc;
enum export export = export_from_sec(info, sym->st_shndx);
enum export export = export_from_sec(info, get_secindex(info, sym));
switch (sym->st_shndx) {
case SHN_COMMON:
......@@ -656,19 +703,19 @@ static const char *sym_name(struct elf_info *elf, Elf_Sym *sym)
return "(unknown)";
}
static const char *sec_name(struct elf_info *elf, int shndx)
static const char *sec_name(struct elf_info *elf, int secindex)
{
Elf_Shdr *sechdrs = elf->sechdrs;
return (void *)elf->hdr +
elf->sechdrs[elf->hdr->e_shstrndx].sh_offset +
sechdrs[shndx].sh_name;
elf->sechdrs[elf->secindex_strings].sh_offset +
sechdrs[secindex].sh_name;
}
static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr)
{
return (void *)elf->hdr +
elf->sechdrs[elf->hdr->e_shstrndx].sh_offset +
sechdr->sh_name;
elf->sechdrs[elf->secindex_strings].sh_offset +
sechdr->sh_name;
}
/* if sym is empty or point to a string
......@@ -1047,11 +1094,14 @@ static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr,
Elf_Sym *near = NULL;
Elf64_Sword distance = 20;
Elf64_Sword d;
unsigned int relsym_secindex;
if (relsym->st_name != 0)
return relsym;
relsym_secindex = get_secindex(elf, relsym);
for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
if (sym->st_shndx != relsym->st_shndx)
if (get_secindex(elf, sym) != relsym_secindex)
continue;
if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
continue;
......@@ -1113,9 +1163,9 @@ static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
const char *symsec;
if (sym->st_shndx >= SHN_LORESERVE)
if (is_shndx_special(sym->st_shndx))
continue;
symsec = sec_name(elf, sym->st_shndx);
symsec = sec_name(elf, get_secindex(elf, sym));
if (strcmp(symsec, sec) != 0)
continue;
if (!is_valid_name(elf, sym))
......@@ -1311,7 +1361,7 @@ static void check_section_mismatch(const char *modname, struct elf_info *elf,
const char *tosec;
const struct sectioncheck *mismatch;
tosec = sec_name(elf, sym->st_shndx);
tosec = sec_name(elf, get_secindex(elf, sym));
mismatch = section_mismatch(fromsec, tosec);
if (mismatch) {
Elf_Sym *to;
......@@ -1339,7 +1389,7 @@ static unsigned int *reloc_location(struct elf_info *elf,
Elf_Shdr *sechdr, Elf_Rela *r)
{
Elf_Shdr *sechdrs = elf->sechdrs;
int section = sechdr->sh_info;
int section = shndx2secindex(sechdr->sh_info);
return (void *)elf->hdr + sechdrs[section].sh_offset +
(r->r_offset - sechdrs[section].sh_addr);
......@@ -1447,7 +1497,7 @@ static void section_rela(const char *modname, struct elf_info *elf,
r.r_addend = TO_NATIVE(rela->r_addend);
sym = elf->symtab_start + r_sym;
/* Skip special sections */
if (sym->st_shndx >= SHN_LORESERVE)
if (is_shndx_special(sym->st_shndx))
continue;
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
......@@ -1505,7 +1555,7 @@ static void section_rel(const char *modname, struct elf_info *elf,
}
sym = elf->symtab_start + r_sym;
/* Skip special sections */
if (sym->st_shndx >= SHN_LORESERVE)
if (is_shndx_special(sym->st_shndx))
continue;
check_section_mismatch(modname, elf, &r, sym, fromsec);
}
......@@ -1530,7 +1580,7 @@ static void check_sec_ref(struct module *mod, const char *modname,
Elf_Shdr *sechdrs = elf->sechdrs;
/* Walk through all sections */
for (i = 0; i < elf->hdr->e_shnum; i++) {
for (i = 0; i < elf->num_sections; i++) {
check_section(modname, elf, &elf->sechdrs[i]);
/* We want to process only relocation sections and not .init */
if (sechdrs[i].sh_type == SHT_RELA)
......
......@@ -129,8 +129,51 @@ struct elf_info {
const char *strtab;
char *modinfo;
unsigned int modinfo_len;
/* support for 32bit section numbers */
unsigned int num_sections; /* max_secindex + 1 */
unsigned int secindex_strings;
/* if Nth symbol table entry has .st_shndx = SHN_XINDEX,
* take shndx from symtab_shndx_start[N] instead */
Elf32_Word *symtab_shndx_start;
Elf32_Word *symtab_shndx_stop;
};
static inline int is_shndx_special(unsigned int i)
{
return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
}
/* shndx is in [0..SHN_LORESERVE) U (SHN_HIRESERVE, 0xfffffff], thus:
* shndx == 0 <=> sechdrs[0]
* ......
* shndx == SHN_LORESERVE-1 <=> sechdrs[SHN_LORESERVE-1]
* shndx == SHN_HIRESERVE+1 <=> sechdrs[SHN_LORESERVE]
* shndx == SHN_HIRESERVE+2 <=> sechdrs[SHN_LORESERVE+1]
* ......
* fyi: sym->st_shndx is uint16, SHN_LORESERVE = ff00, SHN_HIRESERVE = ffff,
* so basically we map 0000..feff -> 0000..feff
* ff00..ffff -> (you are a bad boy, dont do it)
* 10000..xxxx -> ff00..(xxxx-0x100)
*/
static inline unsigned int shndx2secindex(unsigned int i)
{
if (i <= SHN_HIRESERVE)
return i;
return i - (SHN_HIRESERVE + 1 - SHN_LORESERVE);
}
/* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
static inline unsigned int get_secindex(const struct elf_info *info,
const Elf_Sym *sym)
{
if (sym->st_shndx != SHN_XINDEX)
return sym->st_shndx;
return shndx2secindex(info->symtab_shndx_start[sym -
info->symtab_start]);
}
/* file2alias.c */
extern unsigned int cross_build;
void handle_moddevtable(struct module *mod, struct elf_info *info,
......
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